@julian @MatthewHawley Not sure if you got this working or not but you need to specify the application you are adding the addon to:
heroku addons:add redistogo:nano -a myapp
You can also login into the heroku control panel, choose the "Resources" section of your app, click the "Get Add-ons" link and add it there. Terminal is much easier though.
In typical me fashion, I upgraded right away. Per best practices of most changes per window, I installed the 8.x node release and broke npm
After a reinstall of node and npm, all was well in the world.